PRACTICAL ORGANIC CHEMISTRY solvent, such as ether, chloroform, alcohol, amyl alcohol, £c. The solvent is then distilled off, and the alkaloid, which remains, is either crystallised or converted into a crystalline salt. The alkaloids are strong bases, which turn red litmus blue, and are very slightly soluble in water. They form soluble salts and double salts with platinic and auric chlorides. The principal general reagents for the alkaloids are : 1. A solution of iodine in potassium iodide, which forms a reddish-brown precipitate of the periodides. 2. A solution of phosphomolybdic acid in nitric acid, which gives yellow precipitates of different shades. 3. A solution of potassium mercuric iodide, which forms white or yellowish-white precipitates. The constitution of quinine is not yet elucidated. Its relation- ship to quinoline has long been known, since it gives this substance on distillation with caustic potash (Gerhardt). PREPARATION 114. Phenylmethyltriazole Carboxylic Acid.-—The mother substance of this compound is a triazole, viz., pyrro-a/3-diazole, which is one of four isomeric compounds : NH NH NH NH N/\N N/^CH N/\CH HC/Vli UC-—^CH N'J—LCI! HC!—L'N- N----L'N Pyrro-act'-diaicole. Pyrro-ajS-diazole. Pyrro-a/3'-diuzole. Pyrro-jS/J'-cliazule. Pyrro-tt/3-diazole was first obtained by the oxidation of azimido- toluene, which in turn was prepared by the action of nitrous acid on 0-toluylenediamine, CH3 Azimidotoluene. HQ.OC\/ HOOC.C/XN HOOC.C Aximidobenzoic acid. Triazoledicarboxj'lic acid HC iid /\ Pyrro-a^-dia/jolc.